Stonehenge stands as one of the world's most enigmatic prehistoric monuments, consisting of 80 massive standing stones arranged in concentric circles on Salisbury Plain in Wiltshire, England. Built in multiple phases over approximately 1,500 years (construction beginning around 3000 BCE, continuing through 1500 BCE), the monument's exact purpose remains debated—leading theories suggest it served as a healing temple, astronomical observatory, ceremonial center, or burial ground. The larger sarsen stones, weighing 30-50 tons, were transported from 30 kilometers away, while smaller bluestones originated from Wales 250 kilometers distant. Designated a UNESCO World Heritage Site in 1986, Stonehenge attracts approximately 1.5 million visitors annually.